1. Download Windows Security Essentials for Windows 7

2. Right click on mseinstall.exe and select Properties

3. Click the Compatibility tab

4. Check the Run this program in compatibility mode for: box

5. Select Windows 7 from the pull down menu

6. Click OK

7. Open a Command Prompt as Administrator

8. Navigate to the directory with mseinstall.exe

9. At the command prompt type “mseinstall.exe /disableoslimit” without quotes

10. Press enter and install normally